Effect of external strain on the conductivity of AlGaN/GaN high-electron-mobility transistors

The changes in the conductance of the channel of Al0.3Ga0.7N/GaN high-electron-mobility transistor structures during the application of both tensile and compressive strain were measured. For a fixed Al mole fraction, the changes in the conductance were roughly linear over the range up to 2.7×108 N cm−2, with coefficients for planar devices of −6.0+/−2.5×10−10 S N−1 m−2 for tensile strain and +9.5+/−3.5×10−10 S N−1 m−2 for compressive strain. For mesa-isolated structures, the coefficients were smaller due to the reduced effect of the AlGaN strain, with values of 5.5+/−1.1×10−13 S N−1 m−2 for tensile strain and 4.8×10−13 S N−1 m−2 for compressive strain. The large changes in the conductance demonstrate that simple AlGaN/GaN heterostructures are promising for pressure and strain sensor applications.